This study was supported by grants from the Japan Society for the Promotion of Science KAKENHI (https://www.jsps.go.jp/english/index.html) to NU (19K23758, 21K06295), TH (16H06556), and KW (19H03242, 20K21420, 21H00420), from the Ohsumi Frontier Science Foundation (https://www.ofsf.or.jp/en/) to KW, and from the Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials (http://alliance.tagen.tohoku.ac.jp/english/) to NU, TH, and KW.&#160;

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Effects of red background illumination and 3-(3',4'-dichlorophenyl)-1,1-dimethylurea.</a> FEBS Letters. 336 (3), 516-520 (1993).</li><li>Morishita, J., Tokutsu, R., Minagawa, J., Hisabori, T., Wakabayashi, K. 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The authors have nothing to disclose.

The present protocol is easy and not time-consuming. If a C. reinhardtii mutant is suspected of presenting with defects in photoreception or ciliary motion, this method could serve as primary phenotypic analysis.
However, some critical steps exist. One is to use cells in the experiment in the early to mid-log growth phase. After culturing for long periods, cells become less motile, less light-sensitive, and even form palmelloids (cell clumps)27. Another importa...

Light is an indispensable energy source for photosynthetic organisms, but too much light may cause photo-oxidative damage. Thus, phototrophic organisms need to survive under moderate intensity light, where they can photosynthesize but not suffer photo-oxidative damage1. In land plants, chloroplasts cannot move out from the leaf and show photo movements in the cell; chloroplasts move to the periphery of the cell under high light and the cell surface under low light2, whereas many motile algae show photobehaviors that allow them to find proper light conditions for photosynthesis and, thus, facilitate their survival3.
Chlamydomonas reinhardtii is a unicellular green alga regarded as a model organism in research fields like cilia (a.k.a., flagella), photosynthesis, and photobehavior. C. reinhardtii presents with one eyespot and two cilia per cell, used for photoreception and swimming, respectively. The eyespot has two components: channelrhodopsins (ChRs), light-gated ion channels in the plasma membrane, and the carotenoid-rich granule layers located right behind the ChRs. The eyespot acts as a directional light receptor since the carotenoid-rich granule layers function as a light reflector4,5.
ChRs were initially identified as photoreceptors causing photobehaviors in C. reinhardtii6,7,8,9. Although two isoforms, ChR1 and ChR2, are found in the eyespot, knock-down experiments showed that ChR1 is the primary photoreceptor for photobehaviors10. Despite this, ChR2 has received more attention and played a central role in developing optogenetics, a technique to control cell excitation by light11. Therefore, studying the regulatory mechanisms governing photobehaviors in C. reinhardtii will further the understanding of ChR function and improve optogenetics.
After photoreception, C. reinhardtii cells show two types of photobehaviors: phototaxis and photoshock response12. Phototaxis is the behavior of cells swimming in the direction of the light source or the opposite direction, called positive or negative phototaxis, respectively. Photoshock response is a behavior that cells show after sensing a sudden change in light intensity, such as when illuminated by a flash. Cells stop swimming or swim backward (i.e., swimming with the cell body forward) for a short period, typically &#60;1 s.
Ciliary movements in C. reinhardtii are involved in its photobehaviors. Two cilia usually beat like a human&#39;s breaststroke swimming, and this is modulated for photobehaviors. For phototaxis, the forces generated by the two cilia are imbalanced by the modulation of the beating frequency and the waveform amplitude of each cilium13. The cilium closest to the eyespot is called cis cilium, and the other is called trans cilium. These two cilia differ on various points. For example, the ciliary beating frequency of trans cilium in vitro is 30%-40% higher14. In addition, their Ca2+ sensitivity is different. Reactivation of demembranated cell models15 showed that the cis cilium beats more strongly than the trans cilium for Ca2+ &#60;1 x 10&#8722;8 M, while the opposite is true for Ca2+ &#62;1 x 10&#8722;7 M. This asymmetry in Ca2+ sensitivity is possibly important for phototactic turns since mutants lacking this asymmetry do not exhibit normal phototaxis16,17. Conversely, waveform conversion is necessary for photoshock. The ciliary waveform transforms from the asymmetrical waveform in forward swimming to the symmetrical waveform in backward swimming. This waveform conversion is also regulated by Ca2+, at a threshold of 1 x 10&#8722;4 M18,19. Since defects in regulating ciliary movements cause primary ciliary dyskinesia in humans, studying photobehaviors in C. reinhardtii might help in better understanding of these diseases and therapeutic developments20.
Herein, four simple methods to observe photobehaviors in C. reinhardtii are demonstrated. First, a phototaxis assay using Petri dishes is shown, and second, a phototaxis assay against cell suspension droplets. The phenomenon observed in both cases is not strictly phototaxis but photo accumulation, where the cells tend to accumulate close to the light source side or the opposite side. In C. reinhardtii, photo accumulation is mainly caused by phototaxis in a way that can be used as an approximation to phototaxis. Third, a more rigorous assay for phototaxis under a microscope is shown, and last is a photoshock assay under a microscope.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15 mL conical tube</td>
			<td>SARSTEDT</td>
			<td>62.554.502</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mm Cannonball green LED</td>
			<td>Optosupply</td>
			<td>OSPG5161P</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL conical tube</td>
			<td>SARSTEDT</td>
			<td>62.547.254</td>
			<td></td>
		</tr>
		<tr>
			<td>AC adaptor for the light box</td>
			<td>ATTO</td>
			<td>2196161</td>
			<td></td>
		</tr>
		<tr>
			<td>Auto cell counter</td>
			<td>DeNovix</td>
			<td>CellDrop BF</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Nakalai tesque</td>
			<td>06731-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Camera flash</td>
			<td>NEWWER</td>
			<td>TT560</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>KUBOTA</td>
			<td>2800</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlamydomonas strains CC-124 and CC-125</td>
			<td>Chlamydomonas Resource Center</td>
			<td></td>
			<td>https://www.chlamycollection.org/</td>
		</tr>
		<tr>
			<td>C-mout CCD camera</td>
			<td>Wraymer</td>
			<td>1129HMN1/3</td>
			<td></td>
		</tr>
		<tr>
			<td>Desktop darkroom</td>
			<td>Scientex</td>
			<td>B-S8</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital still camera</td>
			<td>SONY</td>
			<td>RX100II</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Dojindo</td>
			<td>G002</td>
			<td></td>
		</tr>
		<tr>
			<td>Fiji</td>
			<td></td>
			<td></td>
			<td>https://fiji.sc/</td>
		</tr>
		<tr>
			<td>Green LED plate</td>
			<td>CCS</td>
			<td>ISLM-150X150-GG</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Fujifilm WAKO</td>
			<td>080-01066</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Dojindo</td>
			<td>GB70</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Nakalai tesque</td>
			<td>238514-75</td>
			<td></td>
		</tr>
		<tr>
			<td>Lightbox (Flat viewer)</td>
			<td>ATTO</td>
			<td>2196160</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>BX-53</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dish (&#966;3.5 cm)</td>
			<td>IWAKI</td>
			<td>1000-035</td>
			<td></td>
		</tr>
		<tr>
			<td>Pottasium acetate</td>
			<td>Nakalai tesque</td>
			<td>28434-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply for the green LED plate</td>
			<td>CCS</td>
			<td>ISC-201-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Red filter</td>
			<td>Shibuya Optical</td>
			<td>S-RG630</td>
			<td></td>
		</tr>
	</tbody>
</table>

observation of photobehavior in chlamydomonas reinhardtii

For the survival of the motile phototrophic microorganisms, being under proper light conditions is crucial. Consequently, they show photo-induced behaviors (or photobehavior) and alter their direction of movement in response to light. Typical photobehaviors include photoshock (or photophobic) response and phototaxis. Photoshock is a response to a sudden change in light intensity (e.g., flash illumination), wherein organisms transiently stop moving or move backward. During phototaxis, organisms move toward the light source or in the opposite direction (called positive or negative phototaxis, respectively). The unicellular green alga Chlamydomonas reinhardtii is an excellent organism to study photobehavior because it rapidly changes its swimming pattern by modulating the beating of cilia (a.k.a., flagella) after photoreception. Here, various simple methods are shown to observe photobehaviors in C. reinhardtii. Research on C. reinhardtii&#39;s photobehaviors has led to the discovery of common regulatory mechanisms between eukaryotic cilia and channelrhodopsins, which may contribute to a better understanding of ciliopathies and the development of new optogenetics methods.

Typical C. reinhardtii phototaxis and photoshock response assays are shown here. After cell density estimation, wild-type cell culture (a progeny of the cross CC-124 &#215; CC-125 with agg1+ mt -)23 was washed with photobehavior experimental solution for the phototaxis dish assay. The cell suspension was placed under dim red light for ~1 h. A 2 mL cell suspension was placed in a 3.5 cm Petri dish. The Petri dish was shaken gently, put on a lightbox, and photographed with a camera fixed on...

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Observation of Photobehavior in Chlamydomonas reinhardtii

Most swimming photoautotrophic organisms show photo-induced behavioral changes (photobehavior). The present protocol observes the said photobehavior in the model organism Chlamydomonas reinhardtii.

Observation of Photobehavior in Chlamydomonas reinhardtii

For the survival of the motile phototrophic microorganisms, being under proper light conditions is crucial. Consequently, they show photo-induced ...

observation-of-photobehavior-in-chlamydomonas-reinhardtii

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3.6K Views.  Hosei University. Most swimming photoautotrophic organisms show photo-induced behavioral changes (photobehavior). The present protocol observes the said photobehavior in the model organism Chlamydomonas reinhardtii.

Video: Observation of Photobehavior in Chlamydomonas reinhardtii

Mating and Tetrad Separation of Chlamydomonas reinhardtii for Genetic Analysis

The unicellular green alga Chlamydomonas reinhardtii (Chlamydomonas) has become a popular organism for research in diverse areas of cell biology and genetics because of its simple life cycle, ease of growth and manipulation for genetic analysis, genomic resources, and transformability of the nucleus and both organelles. Mating strains is a common practice when genetic approaches are used in Chlamydomonass, to create vegetative diploids for analysis of dominance, or following tetrad dissection to ascertain nuclear vs. organellar inheritance, to test allelism, to analyze epistasy, or to generate populations for the purpose of map-based cloning. Additionally, genetic crosses are routinely used to combine organellar genotypes with particular nuclear genotypes. Here we demonstrate standard methods for gametogenesis, mating, zygote germination and tetrad separation. This protocol consists of an easy-to-follow series of steps that will make genetic approaches amenable to scientists who are less familiar with Chlamydomonas. Key parameters and trouble spots are explained. Finally, resources for further information and alternative methods are provided.

Mating and Tetrad Separation of Chlamydomonas reinhardtii for Genetic Analysis

Mating and tetrad separation are required for genetic analysis in Chlamydomonas reinhardtii. Here we demonstrate standard methods for gametogenesis, mating, zygote germination and tetrad dissection. This protocol consists of an easy-to-follow series of steps that will make genetic approaches amenable to scientists who are less familiar with Chlamydomonas.

The unicellular green alga Chlamydomonas reinhardtii (Chlamydomonas) has become a popular organism for research in diverse areas of cell biology and ...

Basic Caenorhabditis elegans Methods: Synchronization and Observation

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has since been used extensively as a model organism 1. C. elegans possesses key attributes such as simplicity, transparency and short life cycle that have made it a suitable experimental system for fundamental biological studies for many years 2. Discoveries in this nematode have broad implications because many cellular and molecular processes that control animal development are evolutionary conserved 3.
C. elegans life cycle goes through an embryonic stage and four larval stages before animals reach adulthood. Development can take 2 to 4 days depending on the temperature. In each of the stages several characteristic traits can be observed. The knowledge of its complete cell lineage 4,5 together with the deep annotation of its genome turn this nematode into a great model in fields as diverse as the neurobiology 6, aging 7,8, stem cell biology 9 and germ line biology 10. 
An additional feature that makes C. elegans an attractive model to work with is the possibility of obtaining populations of worms synchronized at a specific stage through a relatively easy protocol. The ease of maintaining and propagating this nematode added to the possibility of synchronization provide a powerful tool to obtain large amounts of worms, which can be used for a wide variety of small or high-throughput experiments such as RNAi screens, microarrays, massive sequencing, immunoblot or in situ hybridization, among others. 
Because of its transparency, C. elegans structures can be distinguished under the microscope using Differential Interference Contrast microscopy, also known as Nomarski microscopy. The use of a fluorescent DNA binder, DAPI (4',6-diamidino-2-phenylindole), for instance, can lead to the specific identification and localization of individual cells, as well as subcellular structures/defects associated to them.

Basic Caenorhabditis elegans Methods: Synchronization and Observation

The easiness of maintaining and propagating the nematode C. elegans make it a nice model organism to work with. The possibility of synchronizing worms allows the work with a significant amount of subjects at the same developmental stage, what facilitates the study of one particular process in many animals.

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has ...

Flat Mount Preparation for Observation and Analysis of Zebrafish Embryo Specimens Stained by Whole Mount In situ Hybridization

The zebrafish embryo is now commonly used for basic and biomedical research to investigate the genetic control of developmental processes and to model congenital abnormalities. During the first day of life, the zebrafish embryo progresses through many developmental stages including fertilization, cleavage, gastrulation, segmentation, and the organogenesis of structures such as the kidney, heart, and central nervous system. The anatomy of a young zebrafish embryo presents several challenges for the visualization and analysis of the tissues involved in many of these events because the embryo develops in association with a round yolk mass. Thus, for accurate analysis and imaging of experimental phenotypes in fixed embryonic specimens between the tailbud and 20 somite stage (10 and 19 hours post fertilization (hpf), respectively), such as those stained using whole mount in situ hybridization (WISH), it is often desirable to remove the embryo from the yolk ball and to position it flat on a glass slide. However, performing a flat mount procedure can be tedious. Therefore, successful and efficient flat mount preparation is greatly facilitated through the visual demonstration of the dissection technique, and also helped by using reagents that assist in optimal tissue handling. Here, we provide our WISH protocol for one or two-color detection of gene expression in the zebrafish embryo, and demonstrate how the flat mounting procedure can be performed on this example of a stained fixed specimen. This flat mounting protocol is broadly applicable to the study of many embryonic structures that emerge during early zebrafish development, and can be implemented in conjunction with other staining methods performed on fixed embryo samples.

Flat Mount Preparation for Observation and Analysis of Zebrafish Embryo Specimens Stained by Whole Mount In situ Hybridization

The zebrafish embryo is an excellent model for developmental biology research. During embryogenesis, zebrafish develop with a yolk mass, which presents three-dimensional challenges for sample observation and analysis. This protocol describes how to create two-dimensional flat mount preparations of whole mount in situ (WISH) stained zebrafish embryo specimens.

The zebrafish embryo is now commonly used for basic and biomedical research to investigate the genetic control of developmental processes and to model ...

Internalization and Observation of Fluorescent Biomolecules in Living Microorganisms via Electroporation

The ability to study biomolecules in vivo is crucial for understanding their function in a biological context. One powerful approach involves fusing molecules of interest to fluorescent proteins such as GFP to study their expression, localization and function. However, GFP and its derivatives are significantly larger and less photostable than organic fluorophores generally used for in vitro experiments, and this can limit the scope of investigation. 
We recently introduced a straightforward, versatile and high-throughput method based on electroporation, allowing the internalization of biomolecules labeled with organic fluorophores into living microorganisms. Here we describe how to use electroporation to internalize labeled DNA fragments or proteins into Escherichia coli and Saccharomyces cerevisi&#230;, how to quantify the number of internalized molecules using fluorescence microscopy, and how to quantify the viability of electroporated cells. Data can be acquired at the single-cell or single-molecule level using fluorescence or FRET. The possibility of internalizing non-labeled molecules that trigger a physiological observable response in vivo is also presented. Finally, strategies of optimization of the protocol for specific biological systems are discussed.

Studies of biomolecules in vivo are crucial for understanding molecular function in a biological context. Here we describe a novel method allowing the internalization of fluorescent biomolecules, such as DNA or proteins, into living microorganisms. Analysis of in vivo data recorded by fluorescence microscopy is also presented and discussed.

The ability to study biomolecules in vivo is crucial for understanding their function in a biological context. One powerful approach involves fusing ...

Observation and Quantification of Telomere and Repetitive Sequences Using Fluorescence In Situ Hybridization (FISH) with PNA Probes in Caenorhabditis elegans

Telomere is a ribonucleoprotein structure that protects chromosomal ends from aberrant fusion and degradation. Telomere length is maintained by telomerase or an alternative pathway, known as alternative lengthening of telomeres (ALT)1. Recently, C. elegans has emerged as a multicellular model organism for the study of telomere and ALT2. Visualization of repetitive sequences in the genome is critical in understanding the biology of telomeres. While telomere length can be measured by telomere restriction fragment assay or quantitative PCR, these methods only provide the averaged telomere length. On the contrary, fluorescence in situ hybridization (FISH) can provide the information of the individual telomeres in cells. Here, we provide protocols and representative results of the method to determine telomere length of C. elegans by fluorescent in situ hybridization. This method provides a simple, but powerful, in situ procedure that does not cause noticeable damage to morphology. By using fluorescently labeled peptide nucleic acid (PNA) and digoxigenin-dUTP-labeled probe, we were able to visualize two different repetitive sequences: telomere repeats and template of ALT (TALT) in C. elegans embryos and gonads.

Observation and Quantification of Telomere and Repetitive Sequences Using Fluorescence In Situ Hybridization FISH with PNA Probes in Caenorhabditis elegans

We report a concise procedure of fluorescence in situ hybridization (FISH) in the gonad and embryos of Caenorhabditis elegans for observing and quantifying repetitive sequences. We successfully observed and quantified two different repetitive sequences, telomere repeats and template of alternative lengthening of telomeres (TALT).

Telomere is a ribonucleoprotein structure that protects chromosomal ends from aberrant fusion and degradation. Telomere length is maintained by telomerase ...

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

A method for observing and quantifying the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, was established under a stereomicroscope. To improve the mating efficiency of B. Xylophilus and to increase the chances of mating observation, virgin adults were cultured and used for the investigation. Eggs were obtained by keeping the nematodes in water and allowing the females to lay eggs for 10 min. The second-stage juveniles (J2) were synchronized by incubating the eggs for 24 h at 25 &#176;C in the dark, and the early J4 were obtained by culturing the J2 with grey mold, Botrytis cinerea, for another 52 h. At this time point, most J4 nematodes could be clearly distinguished as being male or female using their genital morphology. The male and female J4 were collected and cultured separately in two different Petri dishes for 24 h to get virgin adult nematodes. A virgin male and a virgin female were paired in a drop of water in the well of a concave slide. The mating behavior was filmed with a video recorder under a stereomicroscope. The whole period of the mating process was 82.8 &#177;3.91 min (mean &#177;SE) and could be divided into 4 different phases: searching, contacting, copulating, and lingering. The mean minutes of duration were 21.8 &#177; 2.0, 28.0 &#177; 1.9, 25.8 &#177; 0.7 and 7.2 &#177; 0.5, respectively. Eleven sub-behaviors were described: cruising, approaching, encountering, touching, hooping, locating, attaching, ejaculating, separating, quiescence, and roaming. Interestingly, obvious intra-sexual competition was observed when one female was grouped with 3 males or one male with 3 females. This protocol is useful and valuable, not only in investigating the mating behavior of B. xylophilus, but also in acting as a reference for ethological studies of other nematodes.

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

A protocol for investigating the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, is presented. Behavioral features of B. xylophilus are described in the mating process.

A method for observing and quantifying the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, was established under a stereomicroscope. ...

Dissection and Observation of Honey Bee Dorsal Vessel for Studies of Cardiac Function

The European honey bee, Apis mellifera L., is a valuable agricultural and commercial resource noted for producing honey and providing crop pollination services, as well as an important model social insect used to study memory and learning, aging, and more. Here we describe a detailed protocol for the dissection of the dorsal abdominal wall of a bee in order to visualize its dorsal vessel, which serves the role of the heart in the insect. A successful dissection will expose a functional heart that, under the proper conditions, can maintain a steady heartbeat for an extended period of time. This allows the investigator to manipulate heart rate through the application of cardiomodulatory compounds to the dorsal vessel. By using either a digital microscope or a microscope equipped with a digital camera, the investigator can make video recordings of the dorsal vessel before and after treatment with test compounds. The videos can then be scored at a time convenient to the user in order to determine changes in heart rate, as well as changes in the pattern of heartbeats, following treatment. The advantages of this protocol are that it is relatively inexpensive to set up, easy to learn, requires little space or equipment, and takes very little time to conduct.

The abdominal dorsal vessel of the honey bee and other insects serves as the functional equivalent of the mammalian heart and plays an important role in nutrient transport, waste removal, immune function, and more. Here we describe a protocol for the visualization and pharmacological manipulation of bee heart rate.

The European honey bee, Apis mellifera L., is a valuable agricultural and commercial resource noted for producing honey and providing crop pollination ...

Preparation and Observation of Thick Biological Samples by Scanning Transmission Electron Tomography

This report describes a protocol for preparing thick biological specimens for further observation using a scanning transmission electron microscope. It also describes an imaging method for studying the 3D structure of thick biological specimens by scanning transmission electron tomography. The sample preparation protocol is based on conventional methods in which the sample is fixed using chemical agents, treated with a heavy atom salt contrasting agent, dehydrated in a series of ethanol baths, and embedded in resin. The specific imaging conditions for observing thick samples by scanning transmission electron microscopy are then described. Sections of the sample are observed using a through-focus method involving the collection of several images at various focal planes. This enables the recovery of in-focus information at various heights throughout the sample. This particular collection pattern is performed at each tilt angle during tomography data collection. A single image is then generated, merging the in-focus information from all the different focal planes. A classic tilt-series dataset is then generated. The advantage of the method is that the tilt-series alignment and reconstruction can be performed using standard tools. The collection of through-focal images allows the reconstruction of a 3D volume that contains all of the structural details of the sample in focus.

This report describes a sample preparation protocol and specific imaging conditions for performing scanning transmission electron tomography of thick biological specimens.

This report describes a protocol for preparing thick biological specimens for further observation using a scanning transmission electron microscope. It ...

Isolation and Fluorescence Imaging for Single-particle Reconstruction of Chlamydomonas Centrioles

Centrioles are large macromolecular assemblies important for the proper execution of fundamental cell biological processes such as cell division, cell motility, or cell signaling. The green algae Chlamydomonas reinhardtii has proven to be an insightful model in the study of centriole architecture, function, and protein composition. Despite great advances toward understanding centriolar architecture, one of the current challenges is to determine the precise localization of centriolar components within structural regions of the centriole in order to better understand their role in centriole biogenesis. A major limitation lies in the resolution of fluorescence microscopy, which complicates the interpretation of protein localization in this organelle with dimensions close to the diffraction limit. To tackle this question, we are providing a method to purify and image a large number of C. reinhardtii centrioles with different orientations using super-resolution microscopy. This technique allows further processing of data through fluorescent single-particle averaging (Fluo-SPA) owing to the large number of centrioles acquired. Fluo-SPA generates averages of stained C. reinhardtii centrioles in different orientations, thus facilitating the localization of distinct proteins in centriolar sub-regions. Importantly, this method can be applied to image centrioles from other species or other large macromolecular assemblies.

Isolation and Fluorescence Imaging for Single-particle Reconstruction of Chlamydomonas Centrioles

We have developed a strategy to purify and image a large number of centrioles in different orientations amenable for super-resolution microscopy and single-particle averaging.

Centrioles are large macromolecular assemblies important for the proper execution of fundamental cell biological processes such as cell division, cell ...

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in vitro reactivation of demembranated cells has been a traditional and potent way to examine cell motility. The fundamental advantage of this experimental method is that the composition of the reactivation solution may be easily changed. For example, a high-Ca2+ concentration environment that occurs only temporarily due to membrane excitation in vivo can be replicated in the lab. Eukaryotic cilia (a.k.a. flagella) are elaborate motility machinery whose regulatory mechanisms are still to be clarified. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism in the research field of cilia. The reactivation experiments using demembranated cell models of C. reinhardtii and their derivatives, such as demembranated axonemes of isolated cilia, have significantly contributed to understanding the molecular mechanisms of ciliary motility. Those experiments clarified that ATP energizes ciliary motility and that various cellular signals, including Ca2+, cAMP, and reactive oxygen species, modulate ciliary movements. The precise method for demembranation of C. reinhardtii cells and reactivation of the cell models is described here.

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

The in vitro reactivation of motile cells is a crucial experiment in understanding the mechanisms of cell motility. The protocol describes reactivating the demembranated cell models of Chlamydomonas reinhardtii, a model organism to study cilia/flagella.

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in ...